1. Field of the Invention
The present invention relates generally to a shut-off valve for sprinkler systems and more particularly to a valve which shuts off the water flow through a sprinkler outlet when the sprinkler head has become dislodged.
2. Description of the Prior Art
In a typical sprinkler system such as employed, for example in a lawn, a single water source supplies water simultaneously to several sprinkler outlets, interconnected by a network of underground supply pipes. Generally, at each outlet, a vertical riser pipe extends upward from a T-fitting or elbow in the supply pipe to the surface, where it is capped by a sprinkler head.
When designing a sprinkler system to spread water over a specified area, the water pressure, water flow volume, and the number, placement and type of sprinkler heads must all be considered. If a sprinkler head becomes broken off as by lawn maintenance equipment or becomes otherwise dislodged, the system will generally not function properly. First, the water flow through that particular outlet will increase dramatically due to the reduced resistance. Second, this increased flow will not be dispersed, often causing localized flooding or erosion. Third, the water flow to the remaining outlets will be diminished, causing incomplete watering by the remainder of the circuit.
Therefore, it would be beneficial to have a mechanism which would shut off the water flow through an outlet from which the sprinkler head has Home dislodged. This would prevent the increased, undispersed flow through that particular outlet, as well as the decreased water flow through the remaining sprinklers.
Specific mechanisms have been designed to automatically shut off the flow of water through a sprinkler outlet in the absence of a sprinkler head. Generally, the existing mechanisms rely upon hydraulic pressure--the local increase in water flow due to the missing sprinkler head--to close a valve, thereby shutting off water flow through the outlet.
Such mechanisms, as disclosed for example in U.S. Pat. Nos. 3,976,141; 4,848,661; 5,372,306; 5,523,824; 5,758,682; and 5,857,487 are generally multi-component devices, and require specialized components and/or techniques for installation. The prior devices also do not clearly address the problem of protecting the sprinkler head and riser pipe from damage resulting from an impact that would sever the sprinkler head from the riser pipe.
It is accordingly an object of the present invention to provide a shut-off valve for a sprinkler head, said valve being installable without tools onto sprinkler heads and associated riser pipes of conventional design.
It is a further object of this invention to provide a shut-off valve as in the foregoing object having a durable and simple construction amenable to low cost manufacture.
It is a still further object of the present invention to provide a shut-off valve of the aforesaid nature which affords protection to an associated sprinkler head and riser pipe with respect to impact damage.
These objects and other objects and advantages of the invention will be apparent from the following description.